Infants who need special care are placed in a specialized area, such as a neonatal intensive care unit (NICU), pediatric infant care unit (PICU), cardiac intensive care unit (cICU), etc. within a hospital. Pre-term and term sick newborns that demand a special environment are kept in a warm isolette (at higher temperatures up to 39 deg C.). These delicate newborns demand special care and therefore are generally left in the NICU and are not transported to other hospital sections, including sections for non-invasive imaging-based diagnostic procedures. Thus diagnosis and follow-up patient care is limited to moderately ill infants and is not generally extended to severely ill infants.
Magnetic resonance (MR) imaging is a safe, non-ionizing radiation-based diagnostic imaging tool that is routinely used in the characterization of illnesses of the brain, heart or major organs in the torso (liver, kidney, spleen, pelvis etc.). Diagnosis/prognosis of patients depends on the MR image quality. Patient, user and equipment safety and equipment performance cannot be compromised. Each diagnostic procedure must be carried out in its fullest without being restricted by the equipment.
Additional risks are associated when fragile infants are disturbed, let alone transported outside of their clinical sections. Nevertheless, the benefits of diagnosis outweigh these risks.
An isolette for tomographic examination according to Koch et al. (U.S. Pat. No. 5,800,335 issued Sep. 1, 1998) was of a modular design, but the isolette failed to encompass the entire sub system. Heater switching circuitry used in the isolette produced artifacts during MR scanning. Further, during imaging the isolette is placed inside a RF coil, which compromised image quality as the isolette produced artifacts in the image.
The concept of an RF coil inside the isolette was introduced by Nordell et al. (see International Publication Number WO98/48756 A1, published Nov. 5, 1998). A receive only RF coil was introduced inside the isolette for effective scanning. Fluid flow turbines or related technology was used to propel air needed to achieve even temperatures inside the isolette volume. A stand-alone monitor was used in a base unit situated near the MR patient table to display vital signs of the patient. Signal lines normally stretched from the MR patient table where the patient was placed to the base unit located at the foot of the MR patient table. The unit worked as proposed but the “stretched” lines hampered efficient performance from time to time as they obstructed the patient and thus made it difficult to attend to the patient. For example, when immediate access to the patient was sought one had to carefully juggle his/her way through the lines inside the room.
A solution to this problem was addressed by Rohling et al. (U.S. Pat. No. 6,611,702 issued Aug. 26, 2003) where the entire isolette and the monitoring unit were built on to a GE MRI patient table. The unit was bulky to haul around the hospital, and it took a minimum of three people to maneuver the unit from the NICU to the MR section. The isolette was not modular and thus the entire unit was transported, which limited access to certain sections of the hospital. The RF coil disclosed in Rohling et al. encompassed the entire newborn, the filling factor was low and as a result low signal-to-noise ratios (SNRs) were realized despite the radial extended birdcage RF coil design. The same holds true for Feenan et al. (U.S. Pat. No. 7,599,728 issued Oct. 9, 2009) which was a combination of a neonate incubator with a neonate sized magnetic resonance imaging system. However, the detector RF coil was located outside the neonate incubator and thus image SNR was compromised.
With a magnetic resonance imaging (MRI) compatible transport isolette (Lonnekker et al., U.S. Pat. No. 7,278,962 issued Oct. 9, 2007), patient transfers and hence diagnostic studies are possible. However, the single structural design in which all components are incorporated within the unit resulted in a very long isolette (e.g., over six feet long). The unit was very bulky, weighed roughly ninety-five pounds and was cumbersome to transfer between the trolley and the MRI patient table.
Further, the isolette had an internal motor, and when inserted into the magnet this motor was relatively close to the magnet. As a result, slight lapping with the main magnet bore could cause interaction with the main magnet, with time varying gradients and/or with radiofrequency from the whole body transmit coil. The motor also limited incubator travel on the MRI table and hence infant diagnostic imaging studies. Additionally, close proximity of electronics to the MRI created a source for direct and indirect (from other equipment in the scan room) MRI artifacts in the low signal to noise images, which may be seen as noise bands and can obscure diagnosis.
While temperature regulation in the isolette of Lonnekker was somewhat attained based on feedback from air sensors near patient compartments, the isolette did not adjust to the changing environment, e.g., when being transferred from a relatively warm NICU to a relatively cold MRI scan room. More particularly, patient travel starts in the ICU which is kept warm and thus the equipment is pre-warmed and as a result the isolette quickly attains equilibrium. When the isolette is transferred to MRI scanner, which is significantly cooler than the hospital clinical section (ICU etc.), the isolette, despite its double walled enclosure, has to work harder to reach equilibrium but due to the cooler environment the process is significantly slower. When the unit is returned back to the ICU the opposite occurs. More particularly, due to the transition from the cold environment to the warm environment the unit may reach excessive temperatures and may overheat. Patient skin temperature can be used for thermoregulation and can somewhat assist the regulation process but does not account for environment change and air flow outside the isolette, as commonly encountered in all MRI scanners which are configured to cool patients and the body coil. Elevated temperatures can accelerate brain injury whereas lower temperatures can lead to hypothermia and water loss, both of which are deleterious to the patient.
Additionally, close proximity of the isolette fan to the patient section (aggregate section) introduced excessive audio noise which was not desired by the user or suitable to the patient. Further, a display screen of the isolette may not be viewed if the MRI observation window was not in-line with the MRI magnet bore. Moreover, nearly continuous MR exams on different patients were not possible with this design, as it has to be disinfected between studies delaying the process therefore rendering it inefficient for routine hospital use.
Recently a number of applications from Rapoport regarding neonate closed life support system (US2012/0071745 published Mar. 22, 2012 and US 2013/0267765 published Oct. 10, 2013), life support environment chamber (US 2013/0109956 published May 2, 2013), neonate cradle (US 2014/0039295 published Feb. 6, 2014) and neonate incubator and MRI docking station (US 2014/0128725 published May 8, 2014) have been disclosed. All of Rapoport's applications have one theme in common, to not disconnect the patient from life sustaining and monitoring lines available in the NICU. But efforts to counteract the MRI problems with these lines and monitoring equipment traditionally used in the unit were not discussed, leading to potential confusion as to the operation of the system. Generally, equipment found in the clinical unit are not MRI compatible and thus require re-connecting the patient to MRI compatible accessories or lengthening the existing lines such that the non MRI compatible components are away from the MRI magnet. The smaller the magnet, the smaller the problems and lower the risks (albeit still existent), see Feenan's *728 application for a self-contained incubator system and neonatal MRI combination as well as “Imaging the preterm infant: practical issues by Elia F Maalouf and Serena J Counsell in Part 1, Chapter 2, of book MRI of the Neonatal Brain by Dr. Mary Rutherford, London, Saunders, 2001) which describes a neonatal MRI sized magnet and a cradle (FIG. 2.1 therein).
Recently an MRI compatible infant imaging sub system by Srinivasan (U.S. Pat. No. 8,147,396 issued Apr. 3, 2012) allowed transfer of patients between intensive care and radiology sections where the patient was left undisturbed during inter-section transport including the MRI exam. Improvements to the radio-frequency (RF) coil design for high signal to noise ratio (SNR) and to fit inside this isolette were made by Srinivasan (U.S. Pat. No. 6,992,486 issued Jan. 31, 2006). In addition, compatibility of Lonneker's isolette to MR was described by Srinivasan (see U.S Patent Publication Number 20040116799 published Jun. 17, 2004]), which describes a novel environment adaptable isolette in the best interest of the patient, user and hospital safety.